JP2006220724A - Electrophotographic photoreceptor and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor covering a defect on a conductive support without decreasing excellent electrophotographic characteristics and having excellent repetition stability and environmental characteristics. <P>SOLUTION: The electrophotographic photoreceptor contains a charge transferring agent expressed by a formula (I) in a photosensitive layer, and has a first base coating layer containing a polyimide resin between a conductive support and the photosensitive layer. Since a defect such as a pinhole on the surface of the conductive support is covered and the photoreceptor maintains excellent electrostatic characteristics for a long time, the photoreceptor induces no deterioration in the quality of a printed image even after repeated printing and is superior in printing stability compared to a conventional electrophotographic photoreceptor. In the formula (I), each of 1 to R4 represents one kind of substituent selected from a group consisting of a hydrogen atom, halogen atoms, 1-6C alkyl groups and 1-12C aryl groups, and f is 0 or 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member used in electrophotographic apparatuses such as copying machines, LED (Light Emitting Diode) printers, LD (Laser Diode) printers, and the like, and particularly, an organic photoconductive material having an undercoat layer is used. The present invention relates to an electrophotographic photosensitive member and an electrophotographic apparatus equipped with the photosensitive member.

  In general, an electrophotographic process using a photoconductor is performed as follows. For example, charging is performed by a charging roller as a contact charging system in a dark place, and then an LED or LD is used as an image exposure unit, and an electrostatic latent image is formed by selectively erasing the charge only in the exposed portion. To visualize and form an image.

  Basic characteristics required for such an electrophotographic photosensitive member include being capable of being charged to an appropriate potential in a dark place and having a function of being able to eliminate surface charges by light irradiation.

  The electrophotographic photosensitive member currently in practical use has a basic structure in which a photosensitive layer is formed on a conductive support. However, when a cutting aluminum tube, which is a conductive support, is cut with a diamond bite or the like. Cutting oil or cutting powder remains on the support, and when a photosensitive layer is applied thereon, it appears as a defect during image formation or when a high voltage is applied to the surface of the photoreceptor, the support is cut. There is also a problem that current flows from a defective portion such as burrs, dirt, foreign matter, and the like, causing a partial short.

It also appears as image defects such as dust and fog. Further, since the charge generation layer formed on the conductive support has a thickness of about 1 μm, it is affected by the defects and adversely affects the function as a photoreceptor.
In order not to be affected by such defects on the surface of the conductive support, the conductive support is usually subjected to anodization on the conductive support to provide an alumite film or an undercoat layer using a resin material. A method of covering the above defects has been adopted.

  However, alumite coating has the disadvantage that the fine holes formed on the surface of the anodized coating are contaminated during the manufacturing process, and the surface of the anodized coating is likely to be contaminated in processes such as sealing treatment to close the hole and cleaning treatment. In addition, even if the defects on the surface of the conductive support are coated, the dirt on the anodized film itself has an adverse effect.

  As the undercoat layer, it is known to use resin materials such as polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, silicone resin, polyamide resin, and the like. Of these resins, a polyamide resin is particularly preferable.

However, in an electrophotographic photoreceptor using a polyamide resin or the like for the undercoat layer, the volume resistance value is about 10 ¹² Ω · cm to 10 ¹⁵ Ω · cm, so the thickness of the undercoat layer is 1 μm or less. If the thickness is not reduced, the residual potential is accumulated on the photosensitive member, and the image is dusty or fogged.

  On the other hand, when the film thickness is reduced, not only the defects on the conductive support can be covered, but also the hole injection from the substrate during repeated use is accelerated, the charging potential is remarkably lowered, and the photosensitivity is also lowered. There was a problem that image quality deteriorates due to generation of dust and fog.

A subbing layer using a polyimide resin soluble in an organic solvent and specifically formed with a film thickness of 0.5 μm has also been proposed (see, for example, Patent Document 1).
However, as described in Patent Document 1, in the combination of the undercoat layer in which the film thickness of the undercoat layer containing the polyimide resin is a thin film of less than 1.0 μm and a conventional charge transfer agent, a photoconductor It has been found that there is a problem in that the residual potential after repeated use increases, and dust, fog and the like occur in the image.

In addition, in the case of an electrophotographic apparatus equipped with a contact charging unit that applies a charging voltage by bringing the charging unit into direct contact with the photosensitive member, a high voltage is directly applied to the electrophotographic photosensitive member. There was a problem that the occurrence of such as.
JP-A-8-30007

  An object of the present invention is to provide an electrophotographic photosensitive member that covers defects on a conductive support without impairing excellent electrophotographic characteristics and is excellent in repeated stability and environmental characteristics.

  As a result of intensive studies to solve the above problems, the present inventors have found that in an electrophotographic photoreceptor in which a photosensitive layer is formed on a conductive support via an undercoat layer, the undercoat layer is a specific polyimide. The electrophotographic photosensitive member containing a resin and containing a specific charge transfer agent is found to be free from the problems of the prior art and maintain excellent electrostatic characteristics over a long period of time, thereby completing the present invention. It came to.

  The invention according to claim 1 made based on such knowledge is disposed on the conductive support, the first undercoat layer disposed on the conductive support, and the first undercoat layer. The first undercoat layer contains a polyimide resin, and the photosensitive layer is an electrophotographic photoreceptor containing a charge transfer agent represented by the following general formula [I].

(In the general formula [I], R _{1 to} R ₄ are selected from the group consisting of hydrogen, a halogen atom, an alkyl group having 1 to 6 carbon atoms, and an aryl group having 1 to 12 carbon atoms. Any one type of substituents, and f is 0 or 1.)
The invention according to claim 2 is the electrophotographic photosensitive member according to claim 1, wherein the polyimide resin contained in the first undercoat layer is represented by the following general formula [II] in the chemical structure: An electrophotographic photosensitive member having a repeating unit.

(In the above general formula [II], X is a divalent polycyclic aromatic group in which two aromatic rings are bonded directly or via atoms other than carbon, and n is an integer of 1 or more indicating the degree of polymerization. .)
A third aspect of the present invention is the electrophotographic photosensitive member according to the first or second aspect, wherein the thickness of the first undercoat layer is 1.0 μm or more and 50.0 μm or less. An electrophotographic photoreceptor.
The invention according to claim 4 is the electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the first undercoat layer contains titanium oxide, and the first undercoat The layer is an electrophotographic photosensitive member in which a weight ratio of the titanium oxide to the polyimide resin is 1: 4 or more and 2: 1 or less.
According to a fifth aspect of the present invention, there is provided the electrophotographic photosensitive member according to any one of the first to fourth aspects, wherein the second undercoat layer and the photosensitive layer are provided between the second undercoat layer and the second photosensitive layer. The second undercoat layer is an electrophotographic photosensitive member containing one or both of a thermosetting resin and a thermoplastic resin.
A sixth aspect of the present invention is the electrophotographic photosensitive member according to any one of the first to fifth aspects, wherein the conductive support is an uncut tube.
According to a seventh aspect of the present invention, there is provided an electrophotographic apparatus comprising: the electrophotographic photosensitive member according to any one of the first to sixth aspects; and a charging unit that contacts the surface of the photosensitive layer and charges the photosensitive layer. Device.
An eighth aspect of the present invention is the electrophotographic apparatus according to the seventh aspect, wherein the photosensitive layer includes an exposure unit that irradiates the photosensitive layer with a semiconductor laser and forms a latent image on the photosensitive layer.

  That is, the present invention relates to an electrophotographic photosensitive member in which a photosensitive layer is formed on a conductive support through an undercoat layer, the undercoat layer contains a polyimide resin, and has a general formula as a charge transfer agent in the photosensitive layer. The present invention relates to an electrophotographic photoreceptor comprising a compound represented by [I].

(In the formula, R _{1 to} R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the alkyl group represents another substituent. In some cases, there are both an unsubstituted alkyl group to which no group is bonded and a substituted alkyl group to which another substituent is bonded. The aryl group is bonded to an unsubstituted aryl group to which no other substituent is bonded to another substituent. (Wherein f represents an integer of 0 or 1).
According to the first aspect of the present invention having such a configuration, defects such as pinholes of the conductive support are covered, the increase in the residual potential after repeated use is suppressed, and the occurrence of dust and fog on the image is eliminated. be able to.

  The present invention relates to an electrophotographic photoreceptor, wherein the undercoat layer contains a polyimide resin represented by the general formula [II].

(In the formula, X is a divalent polycyclic aromatic group in which the aromatic ring may be linked by a heteroatom. The two aromatic rings of the polycyclic aromatic group may be directly bonded or a heteroatom. The heteroatom that connects two aromatic rings is an atom other than C, specifically, O or S. The aromatic ring is not particularly limited, but one example is (It is a benzene ring. N is an integer representing the degree of polymerization.)
According to the second aspect of the present invention having such a configuration, it is possible to suppress an increase in residual power after repeated use.

  A third aspect of the present invention relates to the electrophotographic photosensitive member according to the first aspect, wherein the thickness of the undercoat layer is 1.0 μm to 50 μm. According to the third aspect of the invention having such a configuration, it is possible to cover even a relatively large defect portion on the conductive support, and image defects are eliminated.

  According to a fourth aspect of the present invention, in the electrophotographic photosensitive member of the first aspect, when the undercoat layer contains titanium oxide, the dielectric constant of the undercoat layer can be increased and the dispersibility is also improved. Furthermore, the weight ratio of the polyimide resin and titanium oxide is preferably in the range of 2: 1 to 1: 4.

  The invention according to claim 5 is the electrophotographic photosensitive member according to claim 1, wherein the undercoat layer comprises a layer containing a polyimide resin represented by the general formula [II] and a thermosetting resin or thermoplastic resin thereon. By providing the two-layer structure of the layers, the accumulation of residual potential can be suppressed even when the undercoat layer is thickened, and the chargeability is stabilized, so that the image quality is improved.

According to a sixth aspect of the present invention, in the electrophotographic photosensitive member according to the first aspect, the conductive support can be coated with defects on the surface of the conductive support by using a non-cutting tube.
According to the seventh aspect of the present invention, the object of the present invention can be achieved by an electrophotographic apparatus according to the first aspect, wherein the electrophotographic apparatus has a contact charging means as a charging means.

  The electrophotographic photosensitive member of the present invention has no significant deterioration in electrostatic characteristics such as surface potential and post-exposure potential even after repeated, no image defects occur, and is strong in repeated stability. Therefore, according to the present invention, it is possible to provide an electrophotographic photosensitive member having excellent electrophotographic characteristics, cleaning properties, and oil resistance and capable of simplifying maintenance.

Hereinafter, preferred embodiments of the electrophotographic photosensitive member according to the present invention will be described in detail.
The present invention provides, for example, a functionally separated electron in which a charge generation layer containing at least a charge generation agent is formed on a conductive support, and a charge transfer layer containing at least a charge transfer agent is formed thereon. It is applied to a photographic photoreceptor. In this case, a photosensitive layer is formed by the charge generation layer and the charge transfer layer.

  The present invention also provides a single layer type electrophotographic photoreceptor in which a charge generating agent and a charge transfer agent are contained in the same layer (photosensitive layer), a charge transfer layer, and a charge generation layer are laminated in this order to form a photosensitive layer. The present invention can also be applied to the reverse laminated type electrophotographic photoreceptor.

  Examples of the conductive support that can be used in the present invention include aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum, indium, and the like, or a processed body of an alloy thereof. And conductive plates such as metal and carbon treated by vapor deposition, plating, etc. to give conductivity, plastic plates and films, and conductive glass coated with tin oxide, indium oxide, aluminum iodide, etc. The conductive support can be formed using various materials having conductivity without being limited by the type or shape. Moreover, about the shape of an electroconductive support body, the thing of drum shape, rod shape, plate shape, sheet shape, and belt shape can be used.

  Among them, in the present invention, aluminum alloys having an alloy number of JIS H4000 in the 3000s, 5000s, and 6000s are used, and the EI (Extension Ironing) method, the ED (Extension Drawing) method, the DI (Drawing Ironing) method, A conductive support formed by a general method such as II (Impact Ironing) method is preferable. Further, the surface of the conductive support is subjected to surface cutting, polishing, anodizing treatment or the like with a diamond bite. Non-cutting tubes that are not treated are preferred.

  As the charge generating agent that can be used in the present invention, a disazo pigment or oxytitanium phthalocyanine is desirable in terms of good sensitivity compatibility, but is not limited thereto. Others such as selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, metal-free phthalocyanine, other metal phthalocyanine pigments, monoazo pigments, trisazo pigments, polyazo pigments, indigo pigments, selenium pigments, toluidine pigments, pyrazoline pigments, perylene pigments Quinacridone pigments, polycyclic quinone pigments, pyrylium salts, and the like can be used.

  In particular, oxytitanium phthalocyanine has been introduced in several crystal forms. Among them, a maximum diffraction peak is observed at a black angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum using CuKα as a radiation source. Crystal type shown, crystal type showing main diffraction peaks at 7.6 ° and 28.3 °, diffraction with maximum peak at 7.5 ° and other diffraction peak intensities of 7.5 ° A crystal form having an intensity of 20% or less with respect to the peak intensity is particularly preferred for the electrophotographic photoreceptor of the present invention.

  The thickness of the charge generation layer containing the charge generation agent is 0.01 μm or more and 5.0 μm or less, preferably 0.1 μm or more and 1.0 μm or less. The charge generating agent may be used alone or in combination of two or more in order to obtain an appropriate photosensitivity wavelength and sensitizing action.

  The first undercoat layer of the present invention may contain an intermediate (polyimide precursor) before being polyimideized, and the content of the polyimide resin contained in the first undercoat layer is polyimide. The value obtained by multiplying the resin content by the sum of the content of the polyimide resin and the content of the polyimide precursor multiplied by 100 is preferably 20% by weight or more and 70% by weight or less. Is preferably in the range of 30 wt% to 50 wt%.

  If the content of the polyimide resin is less than 20% by weight, the solvent resistance of the first undercoat layer is low, so that a coating solution containing an organic solvent on the first undercoat layer (for example, coating for photosensitive layer) When the liquid or the second undercoat layer coating liquid) is applied, the first undercoat layer is dissolved in the organic solvent. Further, when the content of the polyimide resin exceeds 70% by weight and is in a state close to complete imidization, the residual potential after repeated use is accumulated, resulting in an image defect.

  The molecular weight of the polyimide resin is preferably in the range of 1,000 to 100,000, particularly 10,000 to 30,000. Specific examples of X in the general formula [II] are as shown in the following formulas [X-1], [X-2], and [X-3].

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which a photosensitive layer is formed via a first undercoat layer, and the first undercoat layer contains a polyimide resin represented by the general formula [II]. As a result, the film forming property of the first undercoat layer is improved, and even when the film thickness of the first undercoat layer is thin, defects such as pinholes of the conductive support are covered, and the barrier function of the photosensitive layer , Adhesive function is excellent. An example of the thickness of the first undercoat layer is 1.0 μm or more and 50 μm or less, and preferably 20 μm or more and 40 μm or less.

  The first undercoat layer is formed, for example, by applying and drying a coating liquid containing the above-described polyimide resin and an organic solvent on a conductive support. The drying temperature for forming the first undercoat layer is suitably in the range of 110 ° C. or higher and 170 ° C. or lower, preferably 130 ° C. or higher and 150 ° C. or lower.

  When the drying temperature is less than 110 ° C., the first undercoating layer is dissolved by the solvent, so that the coating solution containing the organic solvent cannot be applied onto the first undercoating layer. When the drying temperature is 110 ° C. or higher, it does not dissolve in the organic solvent. When the drying temperature exceeds 170 ° C., the residual potential after repeated use increases, causing a slight problem that image density changes occur.

  In the electrophotographic photoreceptor of the present invention, the first undercoat layer may contain titanium oxide. The titanium oxide used in the present invention may be subjected to various treatments on the surface of the titanium oxide particles as long as the volume resistance value is not lowered. For example, the surface of the titanium oxide particles can be coated with an oxide film using aluminum, silicon nickel, or the like as a treatment agent. In addition, it is possible to impart water repellency to the titanium oxide particles using a coupling material or the like as necessary. Further, titanium oxide having an average particle diameter of 1 μm or less is preferable, and 0.01 μm or more and 0.5 μm or less is more preferable. The content (weight) of titanium oxide is preferably in the range of 0.5 to 4 times the weight 1 of polyimide.

  On the first undercoat layer containing the polyimide resin represented by the general formula [II], a second undercoat layer further containing a thermosetting resin or a thermoplastic resin is provided, and the undercoat layer is 2 By adopting a layer structure, even if the undercoat layer is thickened, accumulation of residual potential can be suppressed and image quality can be improved.

  Examples of the thermosetting resin include an epoxy resin, polyurethane, phenol, melamine / alkyd resin, and unsaturated polyester resin. These thermosetting resins may be used alone for the second undercoat layer, or two or more kinds may be mixed and used for the second undercoat layer.

  Examples of the thermoplastic resin include styrene elastomers, olefin elastomers, urethane elastomers, and polyvinyl chloride elastomers. These thermoplastic resins may be used alone for the second undercoat layer, or two or more types may be mixed and used for the second undercoat layer. The film thickness of the second undercoat layer provided on the first undercoat layer can be used in the range of 0.1 μm to 10.0 μm, preferably 0.8 μm to 5.0 μm.

  In addition, one or both of the first and second undercoat layers may contain a white pigment for the purpose of suppressing optical interference during semiconductor laser exposure. Examples of the white pigment include titanium oxide, zinc oxide, and silica.

  Examples of binder resins that can be used to form the photosensitive layer include polycarbonate resins, styrene resins, acrylic resins, styrene-acrylic resins, ethylene-vinyl acetate resins, polypropylene resins, vinyl chloride resins, chlorinated polyethers, and chlorides. Vinyl-vinyl acetate resin, polyester resin, furan resin, nitrile resin, alkyd resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, diarylate resin, polysulfone resin, polyethersulfone resin, Polyallyl sulfone resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, EVA (ethylene / vinyl acetate / copolymer) resin, ACS (acrylonitrile / chlorinated) Riechiren styrene) resin, ABS (acrylonitrile butadiene styrene) resins, photocurable resins such as epoxy arylate. These may be used alone or in combination of two or more in the photosensitive layer. In addition, it is more preferable to mix resins having different molecular weights for use in the photosensitive layer since the hardness and abrasion resistance of the photosensitive layer can be improved.

  As the charge transfer agent that can be used in the present invention, among the compounds represented by the general formula [I], the compounds represented by the following formulas [Ia] to [Id] are particularly preferable because of their good compatibility with the polyimide resin. Specific compounds will be shown below, but are not limited thereto.

  The compound represented by the general formula [I] may be used alone in the photosensitive layer, or two or more kinds may be mixed and used in the photosensitive layer.

  In addition to the charge transfer agent represented by the general formula [I], other charge transfer agents described later can be used for the photosensitive layer. When the charge transfer agent represented by the general formula [I] and another charge transfer agent are contained together in the photosensitive layer, the sensitivity of the photosensitive layer can be increased and the residual potential can be lowered. The characteristics of the electrophotographic photoreceptor can be improved.

  Examples of charge transfer agents that can be added to improve such properties include polyvinyl carbazole, halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl pyrazoline, polyacetylene, polythiophene, Conductive polymer compounds such as polypyrrole, polyphenylene, polyphenylene vinylene, polyisothianaphthene, polyaniline, polydiacetylene, polyheptadiene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrocenylene, polyperinaphthylene, polyphthalocyanine, etc. Can be used.

  In addition to the above conductive polymer compounds, as low molecular compounds, trinitrofluorenone, tetracyanoethylene, tetracyanoquinodimethane, quinone, diphenoquinone, naphthoquinone, anthraquinone and derivatives thereof, anthracene, pyrene, phenanthrene, etc. Charges polycyclic aromatic compounds, nitrogen-containing heterocyclic compounds such as indole, carbazole, imidazole, fluorenone, fluorene, oxadiazole, oxazole, pyrazoline, triphenylmethane, triphenylamine, enamine, stilbene, butadiene, hydrazone compounds, etc. It can be added as a transfer agent.

  Also, as a charge transfer agent for the same purpose, a polymer solid electrolyte doped with a metal ion such as Li (lithium) ion to a polymer compound such as polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylic acid or the like is added. You can also.

  Further, as a charge transfer agent for the same purpose, an organic charge transfer complex formed of an electron donating substance typified by tetrathiafulvalene-tetracyanoquinodimethane and an electron accepting substance can be used.

  The charge transfer agent can obtain desired photoreceptor characteristics even when it is added alone or in a mixture of two or more compounds. The film thickness of the charge transfer layer containing the charge transfer agent is 5.0 μm or more and 50 μm or less, preferably 10 μm or more and 30 μm or less.

  In the case of the electrophotographic photoreceptor of the present invention, the total thickness of the photosensitive layer and the base layer (first and second base layers) is preferably in the range of 10 μm to 100 μm, for example, 15 μm or more. A range of 25 μm or less is preferable. For example, when the first and second undercoat layers are provided so as to have a total thickness of about 25 μm, the charge transfer layer may be provided as thin as about 15 μm. On the contrary, when the first and second undercoat layers are provided so as to have a total film thickness of about 1 μm, the charge transfer layer may be provided as thick as about 25 μm.

  For this reason, the pressure resistance of the photoreceptor is required in an electrophotographic process having a contact charging means as a charging means. In general, a photoreceptor having low pressure resistance has a defect generated on the surface from the photoreceptor due to a leak current, and this appears as an image defect. That is, the pressure resistance of the photoreceptor is determined by the total film thickness of the photoreceptor (for example, the total amount of the film thickness of the photosensitive layer and the film thickness of the first and second undercoat layers). By increasing the film thickness, the pressure resistance is improved, so that the charge transfer layer can be made thin.

  The electrophotographic photoreceptor of the present invention is a photoconductive material (for example, charge transfer agent or charge generating agent) or a binder layer, and the photosensitive layer changes due to oxidative degradation, prevents the photosensitive layer from cracking, and the mechanical strength of the photosensitive layer. For the purpose of improving, it is preferable to contain an antioxidant or an ultraviolet absorber in the photosensitive layer.

  Examples of antioxidants that can be used in the present invention include 2,6-di-tert-butylphenol, 2,6-di-tert-4-methoxyphenol, 2-tert-butyl-4-methoxyphenol, 2,4. -Dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, butylated hydroxyanisole, stearyl propionate-β- (3,5-di-tert-butyl-4-hydroxyphenyl ), Α-tocopherol, β-tocopherol, monophenols such as n-octadecyl-3- (3′-5′-di-tert-butyl-4′-hydroxyphenyl) propionate, 2,2′-methylenebis (6 -Tert-butyl-4-methylphenol), 4,4'-butylidene-bis- (3-methyl-) -Tert-butylphenol), 4,4'-thiobis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3 (3,5-di-tert-butyl-4 -Hydroxyphenyl) propionate] Polyphenols such as methane are preferred, and one or more of them can be contained in the photosensitive layer together.

  Moreover, as an ultraviolet absorber, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- ( 3,5-di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-tert-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy -5'-tert-octylphenyl) benzotriazoles such as benzotriazole, phenyl salicylate, salicyl A salicylic acid system such as acid-p-tert-butylphenyl and salicylic acid-p-octylphenyl is preferable, and one or two or more of these may be contained in the photosensitive layer together.

  Further, an antioxidant and an ultraviolet absorber can be added together to the photosensitive layer. Any of these layers may be added to the photosensitive layer, but it is preferably added to the outermost layer, particularly the charge transfer layer.

  The antioxidant is preferably 3% by weight or more and 20% by weight or less with respect to the binder resin of the layer to which the antioxidant is added, and the amount of the ultraviolet absorber added is based on the binder resin. Preferably, the content is 3% by weight or more and 30% by weight or less. Further, when both the antioxidant and the ultraviolet absorber are added, the amount of both components added is preferably 5% by weight or more and 40% by weight or less with respect to the binder resin. In addition, the addition amount with respect to binder resin of the said additive (an ultraviolet absorber or antioxidant) is the value which multiplied 100 by the value which remove | divided the weight of the additive from the total weight of an additive and binder resin. It is.

  In addition to the antioxidant and the ultraviolet absorber, additives such as a light stabilizer such as a hindered amine and a hindered phenol compound, an anti-aging agent such as a diphenylamine compound, and a surfactant may be added to the photosensitive layer.

As a method for forming the photosensitive layer, a method in which a coating solution is prepared by dispersing or dissolving in a solvent together with a predetermined photosensitive material and a binder resin, and coating is performed on a predetermined surface.
As a coating method, dip coating, curtain flow, bar coating, roll coating, ring coating, spin coating, spray coating, and the like can be performed according to the shape of the base and the state of the coating liquid. The charge generation layer can also be formed by a vacuum deposition method.

  Solvents used in the coating solution include alcohols such as methanol, ethanol, n-propanol, i-propanol, butanol, methyl cellosolve, ethyl cellosolve, pentane, hexane, heptane, octane, cyclohexane, cycloheptane, etc. Saturated aliphatic hydrocarbons, aromatic hydrocarbons such as toluene and xylene, chlorinated hydrocarbons such as dichloromethane, dichloroethane, chloroform and chlorobenzene, ethers such as dimethyl ether, diethyl ether and tetrahydrofuran (THF), acetone, methyl ethyl ketone and methyl isobutyl Ketones, ketones such as cyclohexanone, esters such as ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, N, N-dimethylformamide, Methyl sulfoxide, there are amides such as N- methyl-2-pyrrolidone. These may be used alone or as a mixture of two or more solvents.

  Between the first undercoat layer and the photosensitive layer, or between the second undercoat layer and the photosensitive layer, a metal compound, metal oxide, carbon, silica, resin powder, etc. are dispersed in the resin. An intermediate layer can also be formed. Furthermore, various pigments, electron accepting substances, electron donating substances and the like can be contained in the intermediate layer for improving the characteristics.

  In addition, a thin film made of an organic thin film such as polyvinyl formal resin, polycarbonate resin, fluororesin, polyurethane resin, or silicone resin or a siloxane structure formed from a hydrolyzate of a silane coupling agent is formed on the surface of the photosensitive layer. A surface protective layer may be provided as a film. In that case, the durability of the photoreceptor is improved, which is preferable. This surface protective layer may be provided in order to improve functions other than the durability improvement.

  Next, the electrophotographic process and the electrophotographic apparatus of the present invention will be described. In the electrophotographic process of the present invention, known means such as charging means, exposure means, developing means, transfer means, fixing means, and cleaning means can be used.

  As the charging means, a non-contact charging method such as a corona charging method, or a contact charging method in which a charging means such as a charging roller or a charging brush is brought into contact with the photosensitive layer to charge the photosensitive layer can be used. As the light source of the image exposure means, halogen light, fluorescent lamp, laser light or the like can be used. The wavelength of the semiconductor laser is 780 nm or less, preferably 500 nm or more and 780 nm or less, and a method of narrowing the laser beam diameter may be used. The development method may be a dry development method, a wet development method, a two-component, one-component, or magnetic / nonmagnetic development method. As the transfer method, any transfer means such as a roller or a belt may be used.

Hereinafter, examples of the electrophotographic photosensitive member according to the present invention will be described in detail together with comparative examples.
<Example 1>
On a cylindrical drum (conductive support) made of uncut aluminum having a diameter of 30 mm, alumina-coated titanium oxide particles, and the general formula [II] where X is a polyimide resin of the above formula [X-1] A mixture mixed at a ratio of 1: 1 was applied and dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 20.0 μm.

  Next, a melamine amide resin as a thermosetting resin and titanium oxide are mixed in a weight ratio of 1: 2 on the undercoat layer and dissolved in methyl ethyl ketone as a coating solution. It was applied to the surface of the undercoat layer and dried, and a second undercoat layer having a thickness of 18.0 μm was laminated on the first undercoat layer.

  Next, using polyvinyl butyral as a binder resin, oxytitanium phthalocyanine having a maximum peak at an X-ray diffraction intensity of 7.5 degrees and a dispersion in which the binder resin is dispersed are subjected to dip coating to form a second The charge generation layer was formed by coating and drying on the surface of the undercoat layer so that the film thickness after drying was 0.1 μm.

  Next, a polycarbonate copolymer as a binder resin, a butadiene compound of the formula [Ia] as a charge transfer agent, and 2,6-di-tert-butyl-4-methylphenol as an antioxidant, 1.0: A coating solution was prepared by dissolving in tetrahydrofuran at a weight ratio of 0.8: 0.18.

  And after apply | coating this coating liquid to the said charge generation layer surface by dip coating, it dries at the temperature of 120 degreeC for 1 hour, forms a 20 micrometer-thick charge transfer layer, and produces an electrophotographic photoreceptor. did.

<Example 2>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the weight ratio of the polyimide resin and titanium oxide in the first undercoat layer of Example 1 was changed to 2: 1.

<Example 3>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the weight ratio of the polyimide resin and titanium oxide in the first undercoat layer of Example 1 was changed to 1: 4.

<Example 4>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the non-cut aluminum of Example 1 was changed to cut aluminum.

<Example 5>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the first undercoat layer in Example 1 was changed to 1.0 μm.

<Example 6>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the first undercoat layer in Example 1 was changed to 5.0 μm.

<Example 7>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the first undercoat layer in Example 1 was changed to 30.0 μm.

<Example 8>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the first undercoat layer in Example 1 was changed to 50.0 μm.

<Example 9>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the melamine amide resin in the second undercoat layer of Example 1 was changed to nylon resin.

<Example 10>
An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that the charge generation layer was formed on the surface of the first undercoat layer without forming the second undercoat layer.

<Example 11>
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that the charge transfer agent of formula [Ia] in Example 1 was changed to the charge transfer agent of formula [Ib].

<Example 12>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent of formula [Ic] was used in the charge transfer layer in addition to the charge transfer agent of formula [Ia] of Example 1.

<Example 13>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent of formula [Id] was used in the charge transfer layer in addition to the charge transfer agent of formula [Ia] of Example 1.

<Example 14>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the first undercoat layer in Example 1 was changed to 0.5 μm.

<Comparative Example 1>
Electrophotography by the same method as in Example 1 except that anodized anodized layers were formed instead of the first and second undercoat layers in Example 1 and a charge generation layer was formed on the surface of the anodized layer. A photoconductor was prepared.

<Comparative example 2>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the first undercoat layer of Example 1 was not formed and the second undercoat layer was formed on the surface of the conductive support.

<Comparative Example 3>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the first and second undercoat layers of Example 1 were not formed, and the charge generation layer was formed directly on the surface of the conductive support.

<Comparative example 4>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the hydrazone compound represented by the following formula [A] was used instead of the charge transfer agent represented by the formula [Ia] in Example 1. did.

<Comparative Example 5>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that nylon resin was used instead of the polyimide resin in the first undercoat layer of Example 1.
The film thicknesses of the first and second undercoat layers, the composition of the second undercoat layer, the type of electrolytic transfer agent, and the conductive support of Examples 1 to 16 and Comparative Examples 1 to 5 Table 1 below shows combinations of these types.

<Evaluation test: measurement of electrostatic characteristics, repeated cycle test, image test>
Examples 1 to 16 and Comparative Examples using a contact charging type printer (trade name “Microline 14” manufactured by Oki Data Co., Ltd.) in an environment of normal temperature and humidity (24 ° C., 40% RH) The cylindrical electrophotographic photosensitive member produced according to 1 to 5 is charged so that the surface potential of the photosensitive member after charging is −800V, and the initial setting is performed so that the surface potential of the photosensitive member after LED exposure is −50V. Subsequently, the surface potential V0 (−V) and the residual potential VR (−V) after printing 20,000 sheets of A4 paper were measured. In the image test, images after continuous printing of 20,000 sheets were evaluated. The results are shown in Table 1. In the determination, “◯” indicates a good one, and “×” indicates that there is a problem in practical use due to an image defect or the like.

  “Density reduction” was defined as “◯” when the density of the printed image was observed to be lower than that at the start of printing after continuous printing of 20,000 sheets, and “X” when the density was not decreased.

  “Black” indicates “x” when a lot of black spots are confirmed in an area where an image is not formed, “△” when several spots are confirmed, and “○” when no spots are confirmed. It was.

  “Chile, fogging” was evaluated as “X” when the toner is attached to the non-image portion that should be white, and “◯” when the toner is not attached.

  In “leak resistance”, in the evaluation by an image, when there is a leak phenomenon, a black spot is formed on the white background image, “x” is given when such a black spot is present, and “◯” is given when there is no black spot.

“Transfer memory” is a phenomenon in which an afterimage printed in the previous cycle is printed in the next cycle in image evaluation. When the afterimage is formed on the image, “x”, and no afterimage is formed. The case was set as “◯”.
The measurement results of the evaluation test are shown in Table 2 below.

As is apparent from Table 2 above, the electrophotographic photoreceptors of Examples 1 to 14 are excellent in chargeability and light fatigue characteristics after repeating 20,000 sheets, and image defects such as dust and fog are completely absent in the image. Did not occur.
In addition, good results were obtained even when titanium oxide was mixed with polyimide resin or when a thermosetting resin or thermoplastic resin was laminated on the polyimide resin layer.

  On the other hand, as in Comparative Examples 2 and 3, when there was no polyimide resin layer, black spots, dust, and fogging occurred due to the transfer memory. Further, in Comparative Example 5 in which the first undercoat layer is made of a resin other than polyimide resin, all the evaluation tests for leakage resistance, transfer memory, dust, fog, density reduction, and black spot were unpractical. It was.

Claims (8)

A conductive support; a first undercoat layer disposed on the conductive support; and a photosensitive layer disposed on the first undercoat layer;
The first undercoat layer contains a polyimide resin,
The photosensitive layer is an electrophotographic photosensitive member containing a charge transfer agent represented by the following general formula [I].

(In the general formula [I], R _{1 to} R ₄ are selected from the group consisting of hydrogen, a halogen atom, an alkyl group having 1 to 6 carbon atoms, and an aryl group having 1 to 12 carbon atoms. Any one type of substituents, and f is 0 or 1.) The electrophotographic photosensitive member according to claim 1, wherein the polyimide resin contained in the first undercoat layer has a repeating unit represented by the following general formula [II] in a chemical structure.

(In the above general formula [II], X is a divalent polycyclic aromatic group in which two aromatic rings are bonded directly or via atoms other than carbon, and n is an integer of 1 or more indicating the degree of polymerization. .)   The electrophotographic photosensitive member according to claim 1, wherein the film thickness of the first undercoat layer is 1.0 μm or more and 50.0 μm or less. The first subbing layer contains titanium oxide;
4. The electrophotographic photosensitive member according to claim 1, wherein the first undercoat layer has a weight ratio of the titanium oxide and the polyimide resin of 1: 4 or more and 2: 1 or less. 5. . A second undercoat layer is disposed between the first undercoat layer and the photosensitive layer,
5. The electrophotographic photosensitive member according to claim 1, wherein the second undercoat layer contains one or both of a thermosetting resin and a thermoplastic resin.   The electrophotographic photosensitive member according to claim 1, wherein the conductive support is a non-cutting tube. An electrophotographic photoreceptor according to any one of claims 1 to 6,
An electrophotographic apparatus comprising: charging means for charging the photosensitive layer in contact with the surface of the photosensitive layer.   The electrophotographic apparatus according to claim 7, further comprising an exposure unit that irradiates the photosensitive layer with a semiconductor laser to form a latent image on the photosensitive layer.